single-user login program

Slogin is a login program to be used in single-user mode. It
prompts the user:

root password (or ^D to log in as a user):

and waits for input.

If the user supplies the root password, slogin immediately
initiates a root login session. Otherwise, if the user presses
Control-D, the program prompts for user name and password and
initiates a non-superuser session, provided that the supplied credentials are
correct.

In both cases slogin does not try to write any files, in
particular, it does not modify /var/log/utmp and
/var/log/wtmp. This makes it useful in start-up scripts,
when the root maintenance is necessary, escpecially when the partition
containing these files is not mounted (e.g. fsck failed).